1. Field of the Invention
The present invention relates to a recording medium having a natural texture of kenaf paper with excellent characteristics for images, and an ink jet recording method using the recording medium in which ink droplets fly for recording.
1. Related Background Art
The ink jet recording system is a recording method for images and characters by letting minute ink droplets fly and attach to a recording medium such as paper based on various operation principles. The feature of the system includes high-speed printing, low-noise operation, easy adaptation for multi-color printing, and adaptability for various recording patterns, as well as the absence of image fixation process. Recently, the system has been widely used no only for recording images such as characters in monochrome, but also in recording full-color images. Moreover, not limited its use to business machines, this system is rapidly spreading in various fields, such as industry and art creation.
Various materials are used for the recording medium of the ink jet recording system, including not only ordinary paper made of ordinary wood pulp such as copy paper and bond paper, but also various coated sheets each having an image forming layer on its surface, transparent film formed of synthetic resin for OHP, textile of various fibers and the like. Among these, the amount of plain paper used as a recording medium has been remarkably increasing with recent popularization of personal computers, and office automation.
According to the popularization of the ink jet system, various properties are required for the recording medium, such as rapid ink-absorbency, high ink-absorbing capacity, and improved image density and printing quality on printing, as far as increased water resistance of printed matters. It is especially required for the recording medium to allow the ink jet attached to the recording medium quickly to penetrate into the medium and apparently become dry on the surface. Furthermore, since a water-base ink is usually used in the ink jet system, resulting in poor drying properties, a phenomenon called cockling may occur, i.e., the printed portion may become wavy, especially when paper made of cellulose pulp is used as the recording medium.
To solve these problems, Japanese Patent Application Laid-Open No. 55-51583 discloses that a coat layer of amorphous silica and a high-molecular binder provides the high ink absorbency for water-base ink printing, and is suitable for high-speed printing. Therefore, the application of such a coat layer as an ink-receiving layer for the ink jet recording medium seems to be effective.
Kenaf has been attracting attentions as a pulp material for paper production, a substituent for pulp wood. Kenaf pulp made from kenaf is largely classified in the total trunk pulp obtained by pulping both ligneous and bast portions, the bast pulp obtained by pulping only the bast portion, and the ligneous pulp obtained by pulping only the ligneous portion. The kenaf paper mainly made of the kenaf pulp has a texture like Japanese paper, with such properties as bulkiness, large ink-absorbing capacity, and excellent ink-receptibility.
A paper recording medium such as kenaf having an excellent ink absorbency and a large ink-absorbing capacity has a problem that feathering or printing-through occurs when the ink is applied. Furthermore, the printed portion of recording medium is disadvantageously elongated becoming wavy, i.e., so-called cockling occurs. Thus, the kenaf paper excellent in both ink absorbency and image quality properties has not been obtained yet. If an ink receiving layer is formed on a kenaf paper surface to improve the above-mentioned shortcomings, ink jet recording properties such as the ink absorbency and suitability for high-speed printing can be improved, but there is a problem that the natural texture of kenaf paper is lost, and when an ink receiving surface is white, black ink turns to brown, with poor quality of formed full-color image.